Wind power and the use of wind turbines have gained increased attention as the quest for alternative energy sources continues. Wind power may be considered one of the cleanest, most environmentally friendly energy sources presently available. Different from traditional fossil fuel sources, wind power is completely renewable and does not produce noxious or environmentally harmful bi-products. With an increasing attention towards generating more energy from wind power, technological advances in the art have allowed for increased sizes of wind turbines and new designs of wind turbine components. However, as the physical sizes and availability of wind turbines increase, so does the need to balance the cost of manufacturing and operating wind turbines to further allow wind power to be cost-competitive with other energy sources.
A modern wind turbine typically includes a tower, generator, a gearbox, a nacelle, and one or more rotor blades. The rotor blades capture the kinetic energy of wind using foil principles known in the art. The rotor blades transmit the kinetic energy in the form of rotational energy so as to turn a shaft coupling the rotor blades to a gearbox, or if a gearbox is not used, directly to the generator. The generator then converts the mechanical energy to electrical energy that may be deployed to a utility grid.
The size, shape, and weight of rotor blades are factors that contribute to energy efficiencies of wind turbines. For example, an increase in rotor blade size increases the energy production of a wind turbine, while a decrease in weight also furthers the efficiency of a wind turbine. Furthermore, as rotor blade sizes grow, extra attention needs to be given to the structural integrity of the rotor blades. Presently, large commercial wind turbines are capable of generating between one and one-half megawatts to five megawatts of power. Some of the larger wind turbines have rotor blade swept areas larger than 90 meters in diameter. Additionally, advances in rotor blade shape encourage the manufacture of a swept-shaped rotor blade having a general arcuate contour from the base to the tip of the blade, providing improved aerodynamics. Accordingly, efforts to increase rotor blade size, decrease rotor blade weight, and increase rotor blade strength, while also improving rotor blade aerodynamics, aid in the continuing growth of wind turbine technology and the adoption of wind energy as an alternative energy source.
In order to achieve higher performing blades with increased annual energy production, “flatback” airfoils have been tested and used for the inboard section of the blade. Compared to thick conventional, sharp trailing-edge airfoils, a flatback airfoil with the same thickness exhibits increased lift and reduced sensitivity to fouling. These previous designs have incorporated the flatback concept into the skin, by opening up the trailing edge of the airfoil uniformly along the camber line. While offering improved performance, the structure of these previous designs is not reliable in all circumstances.
It would, therefore, be beneficial to provide a structural flatback airfoil insert which provides aerodynamic performance and significant energy capture capability. It would also be beneficial to provide a structural flatback airfoil which adds to the stability of the blade and which may replace other structural members such as the auxiliary shear webs.